1. Field of the Invention
The present invention relates to a surface-emitting laser diode in which different emission directions can be realized.
2. Description of the Related Art
European Patent Document EP-A-0 442 002 describes a radiation-generating semiconductor component in which there are present on the surface of the semiconductor material spatial periodic structures which are coated with a thin metallic film. Surface plasmon polaritons are excited on the surface of this metallic film by photons generated in the active layer. An extremely focused emission from the surface is achieved by this excitation of surface modes. Surface plasmon polaritons are transverse electric (TE) or transverse magnetic (TM) surface modes which can propagate at the interface between two different media. The excitation of these modes requires a suitable periodic structure of the interface, which is formed in the case of the component described by a spatial structure, produced by etching, for example, of the semiconductor surface. The loss mechanisms which occur in conventional radiation-generating components and limit efficiency can be avoided, a greatly reduced line width of the emitted light and a drastic increase in the external quantum efficiency being achieved simultaneously. The emission takes place, in addition, with a defined polarization direction which is fixed by the arrangement and alignment of the periodic surface structure.
European Patent Document EP-A-0 360 011 describes a tunable DFB laser diode in which the active layer and the tuning layer are arranged transversely relatively to one another and can be driven separately via an intermediate layer which is located therebetween. This laser diode, known to experts as a TTG-DFB laser diode, has come to exist in the meantime in various modifications which relate, in particular, to various arrangements of the contacts required for the supply leads. Such diodes can be constructed on conductive and on semi-insulating substrates. The layer structure can be adapted in detail to the respective requirements, in particular in the case of the production of highly integrated components.